A rhinoceros (often abbreviated to rhino), from Greek rhinokeros, meaning nose-horned, from rhinos, meaning nose, and keratos, meaning horn).

The family Rhinocerotidae consists of five extant species of odd-toed ungulates, as well as any of the numerous extinct species. Two of the extant species are native to Africa and three to Southern Asia.

The white rhinoceros is the largest extant species of rhinoceros. It has a wide mouth used for grazing and is the most social of all rhino species.

The white rhinoceros consists of two subspecies: the northern white rhinoceros and the southern white rhinoceros.

The northern white rhinoceros (Ceratotherium simum cottoni) has only three animals still living, all in captivity, two females; Fatu, 15 and Najin, 25: and one male; Sudan, 42.

The southern rhinoceros (Ceratotherium simum simum) has an estimated twenty thousand animals still living in the wild, most of which live in South Africa.

The southern white rhinoceros is one of largest and heaviest land animals in the world. It has an immense body and large head, a short neck and broad chest. Females weigh 1,700 kg (3,750 lb) and males 2,300 kg (5,070 lb).

The Sumatran rhinoceros is the smallest extant rhinoceros species and the one with the most hair. It can be found at very high altitudes in Borneo and Sumatra.

Due to habitat loss and poaching, their numbers have declined making it the most threatened rhinoceros with only 275 Sumatran rhinos remaining.

There are three subspecies of Sumatran rhinoceros: the Sumatran rhinoceros proper (Dicerorhinus sumatrensis sumatrensis), the Bornean rhinoceros (Dicerorhinus sumatrensis harrissoni) and the possibly extinct Northern Sumatran rhinoceros (Dicerorhinus sumatrensis lasiotis).

The name black rhinoceros was chosen to distinguish this species from the white rhinoceros which is confusing because the two species are not distinguishable by color.

There are four subspecies of the black rhinoceros:

South-central (Diceros bicornis minor), the most numerous, which once ranged from central Tanzania south through Zambia, Zimbabwe and Mozambique to northern and eastern South Africa;

South-western (Diceros bicornis occidentalis) which are better adapted to the arid and semi-arid savannas of Namibia, southern Angola, western Botswana and western South Africa;

East African (Diceros bicornis michaeli), primarily in Tanzania; and

West African (Diceros bicornis longipes) which, sadly was declared extinct in November 2011.

The native Tswanan name keitloa describes a South African variation of the black rhino in which the posterior horn is equal to or longer than the anterior horn.

The Javan rhinoceros is one of the most endangered large mammals in the world, with only about 60 remaining, and in the wilds of Java, Indonesia. These animals prefer dense lowland rain forest, tall grass and reed beds that are plentiful with large flood plains and mud wallows.

It is also the least known rhino species. Like the closely related, and larger, Indian rhinoceros, the Javan rhino has a single horn. Its hairless, hazy gray skin falls into folds into the shoulder, back, and rump, giving it an armored appearance.

Its length reaches 3.1 to 3.2 m (10 to 10.5 ft) including the head, and its height 1.5 to 1.7 m (5 feet to 5.5 feet). Adults are variously reported to weigh 900 to 2,300 kg (or 2,000 to 5,000 pounds.) Male horns can reach 26 cm in length, while in females they are knobs or altogether absent.

The Indian rhinoceros, or greater one-horned rhinoceros, has a single horn 20 to 60 cm long and is nearly as large as the African white rhinoceros. Its thick, silver-brown skin forms huge folds all over its body. Its upper legs and shoulders are covered in wart-like bumps, and it has very little body hair.

The adult males are larger than females in the wild and weighing from 2,500 to 3,200 kg (5,500 to 7,100 pounds). Shoulder height is 1.75 to 2.0 m (5.7 feet to 6.6 feet). The record-sized specimen was approximately 3,800 kg (8,400 pounds).

Females weigh about 1,900 kg (4,200 pounds) and are 3 to 4 m (9.8 feet to 13 feet) long.

Indian rhinos once inhabited many areas ranging from Pakistan to Myanmar and maybe even into parts of China. However, because of human interference, they now only exist in several protected areas of India and Nepal, plus a few pairs in Lal Suhanra National Park in Pakistan.

Two-thirds of the total population of Indian rhinoceroses are now confined to the Kaziranga National Park situated in the Golaghat district of Assam, India